My only negative comment was that it did feel a little bit like Moffat's Greatest Hits. All it was missing was Sally Sparrow. We had the Weeping Angels, River Song and the disembodied voice (as used in Silence in the Library). All sounds good and is, the negative point being that it feel a little bit of a rehash - especially the voice thing.
I did love River Song's escape from the Byzantium, very 25th Century James Bond. Moffat clearly has long term plans for her, but they will clearly not be solved within this Doctor's lifespan. I liked the fact her note book/diary looked like the TARDIS as well.
I also like how the crack in time and space is appearing. I thought I noticed it in the video of the Angel during this episode and the trailer for next week shows it being a major part of the story. The story arcs under RTD, was for once, were far too subtle. You'd get the occasionally throwaway reference or the eagle eyed viewer would notice something, but nothing would really happen until the last 4 episodes.
Also, on another note, this episode looked amazing. The Byzantium design was pretty retro - Flash Gordon/Buck Rogers style. Location shooting also helps a lot! You can always tell a studio even if we have moved on from the days of Star Trek always using the same set, but with different coloured polystyrene rocks.
Matt Smith is making an excellent Doctor. His youth is forgotten about and while he does occasionally do a bit of a Tennant impression, he is very much a very different Doctor. Amy Pond is the most fanciable assistant so far.
So yeah, roll on next Saturday!